Conventionally, PTL 1 discloses a brake device including a rotary pump. FIG. 6 is a cross sectional view of a pump body including the rotary pump installed to this conventional brake device. As is shown in this drawing, disposed are seal structures J5, J6 having resin annular members J5a, J6a and rubber annular members J5b, J6b between a drive shaft J3 for driving rotary pumps J1, J2 and a casing J4 for housing the rotary pumps J1, J2. These seal structures J5, J6 prevents brake fluid from leaking between the drive shaft J3 and the casing J4.
More specifically, the seal structure J5, J6 are disposed so that the resin annular members J5a, J6a are in contact with the drive shaft J3, and that the rubber annular members J5b, J6b are in contact with the casing J4. Friction between the rubber annular members J5b, J6b and the casing J4 would cause wearing or peeling of the rubber annular members J5b, J6b if the resin annular members J5a, J6a and the rubber annular members J5b, J6b rotated together with the drive shaft J3. Therefore, the seal structures J5, J6 are structured so that the resin annular members J5a, J6a and the rubber annular members J5b, J6b do not rotate relative to the casing J4.
For example, as shown in FIG. 7 which is a Z-Z cross sectional arrow view of FIG. 6, a protruding portion J5d is formed at an outer periphery of an annular cover separator J5c which is fixed to the resin annular member J5a, and a key groove J4a is formed at a part of the casing J4 corresponding to the protruding portion J5d. This structure prevents the resin annular member J5a from rotating relative to the casing J4. Therefore, this structure also prevents the rubber annular member J5b located at the outer periphery of the resin annular member J5a from rotating relative to the casing J4.
In addition, as shown in FIG. 6, the seal structure J6 includes a pin J6c for preventing rotation of the resin annular member J6a. This rotation preventing member composes a structure for preventing the resin annular member J6a from rotating relative to the casing J4. Therefore, this structure also prevents the rubber annular member J6b located at the outer periphery of the resin annular member J6a from rotating relative to the casing J4.